title: Purification and characterization of beta-galactosidase from a strain of Bacillus coagulans.
abstract: beta-Galactosidase from B. coagulans strain L4 is produced constitutively, has a mol. wt. of 4.3 x 10(5) and an optimal temperature of 55 degrees C. The optimal pH at 30 degrees C is 6.0 whereas at 55 degrees C it is 6.5. The energy of activation of enzyme activity is 41.9 kJ/mol (10 kcal/mol). No cations are required. The Km with ONPG as substrate is 4.2-5.6 mM and with lactose is 50 mM. The Ki for inhibition by galactose is 11.7-13.4 mM and for dextrose is 50 mM. Galactose inhibited competitively while dextrose inhibited noncompetitively. The purified and unprotected enzyme is 70% destroyed in 30 min at 55 degrees C whereas in the presence of 2 mg/ml of BSA 42% of the activity is destroyed in 30 min at 55 degrees C. An overall purification of 75.3-fold was achieved.
mesh_terms: D001407:Bacillus / Q000201:enzymology*; D002241:Carbohydrates / Q000494:pharmacology; D002412:Cations / Q000494:pharmacology; D004790:Enzyme Induction; D005696:Galactosidases / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007785:Lactose; D008970:Molecular Weight; D013696:Temperature; D001616:beta-Galactosidase / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D002241:Carbohydrates; D002412:Cations; D005696:Galactosidases; D001616:beta-Galactosidase; D007785:Lactose